In all digital module manufacturing industries today, hundreds of thousands of printed circuit boards must be assembled with proper components mounted therein with subsequent passage through a soldering process whereby one side of the printed circuit board is subject to a soldering operation whereby hundreds of terminal points are soldered for reliable electrical connectivity.
In this manufacturing process, general usage is made of wave soldering machines whereby a conveyer having conveyer fingers will carry sequences of printed circuit boards in forward motion along a pair of guard rails whereby the underside of the printed circuit board is passed over a molten bath of solder which is agitated to rise in waves against the underside of the printed circuit board.
In this particular operation which is repeated thousands of times in digital unit manufacturing operations, it has been the standard practice to "protect" one side of the printed circuit board from being wetted or contacted by the hot molten solder. This particular protected portion of the printed circuit board is the portion comprising a series of gold contacts which connect the components mounted on the printed circuit board to the mother board or other types of connectors for operation in a ditial unit.
The general practice has been to manually apply Kapton tape to the gold contact area of each of the thousands of printed circuit boards so that when the printed circuit board passes over the wave solder pot, it is essentially insulated from contact by the hot molten solder.
There are many disadvantages to this method of protecting the gold contact areas. Since the Kapton tape is not only an unusually expensive item which is used in large quantities, but additionally, considerable and precise labor time is involved in both applying the Kapton tape initially and subsequently removing the tape from the gold plated contacts. Unfortunately, various levels of contamination of the gold contact area can occur due to the application of the adhesive Kapton tape with undesired results.
It has long been an annoying problem to attempt to find a better method of accomplishing the wave solder operation without contamination or degradation of the gold contacts.
Various attempts have been made to provide other forms of shielding devices to prevent the molten solder from wetting the gold contact area, but to this date, no outstandingly successful and efficient methods have been developed.
The presently disclosed system for efficient prevention of any solder-wetting or contact to the gold connection areas on the printed circuit board describes an apparatus which can be fitted onto a wave solder machine and which will provide a finger shield in proximity to the printed circuit board such that the hot molten solder is prevented from approaching the area of the printed circuit board which carries the gold connecting contact areas.